Perth days for the first half of January are averaging the hottest since 1962.  Only two days this month so far have stayed below 30 degrees - and then barely - pushing the average maximum for the month so far up to 33.6 degrees, 2.5 degrees above average.

This comes after a December that was, in its entirety, the second warmest on record. 

It's becoming a theme this summer for the western capital, with temperatures this week forecast to reach the mid-thirties or higher for the next 6 days.  The hottest day is likely to be Tuesday, 19th January.  

In other western centres, it has also been hot, with Geraldton having its hottest first half of January since records began in 2012.  The northern town has already had 5 days over 40 degrees this month and 10 above 35, compared to 0 and 6 for the whole of January last year.  Like Perth, this follows on from a December that was the second hottest, in terms of daytime maxima, on record.

Further south, Bunbury is averaging 32.1 degrees so far this month, 2.3 degrees above average and the hottest daytime start to January since records began in 1996.  Here, too, December was the one of the hottest on record, coming in at third on the ranking list.  

Image: Mean sea level pressure and near surface temperature according to the ECMWF model for the afternoon of Tuesday 19th January showing a high pressure system to the south and a trough near the west coast.  

The weather pattern responsible for the heat has been prolonged periods of northeasterly winds as high pressure systems sit to the south of the continent and troughs to the west, drawing hot air from the interior over the west coast and largely inhibiting deep cold air behind fronts penetrating far north or inland.